Medicare Adjustment Modifier AT & GA filed to Palmetto
The Medicare contractors have some leeway in the interpretation of the rules. Cahaba allowed chiropractors to modify the adjustment with ATGA. However, it appears that Palmetto does not allow this.
The AT modifier is used to indicate that the chiropractic adjustment is provided as an active/corrective treatment for an acute or chronic subluxation and that you reasonably expect the service to be reimbursed under the program.
The GA modifier is used when the physician believes the service will likely be denied for medical necessity and that he has obtained a valid Advanced Beneficiary Notice (ABN) prior to the service being performed.
Short version; the AT modifier says that you expect the service to be reimbursed and the GA modifier says that you expect the service to be denied. So, if you are filing your Medicare claims to Palmetto, the AT modifier and the GA modifier are exclusive – you can use one or the other but not both.
The Claim Adjustment Reason Code (CARC) used is CO-4 – The procedure code is inconsistent with the modifier used or a required modifier is missing.
There are eleven modifiers that apply to the chiropractic adjustment. These are covered in detail in our Medicare Online Course.